Online storage services, as well as other services, are frequently targets for abuse. Among such services is the Windows® Live suite of services offered by Microsoft Corp. A typical abuse scenario involves a person opening a new account, uploading a large number of files, and distributing the files on a file sharing site from the storage service.
There exist a number of abuse mitigation measures that attempt to address this and other problems. However, many of the abuse mitigation measures are reactive in the sense that the measures monitor a specific account over an extended period of time to ascertain whether the account follows particular patterns associated with abuse. Such patterns can include using an inordinate amount of bandwidth over time, receiving too many requests for files over time, and the like. These and other measures, however, tend to be ineffective with respect to new users. This is because new users do not have a history of past activities over time to serve as a basis for making a decision with respect to the particular user. Some systems have imposed strict restrictions on new users or have forced new users to validate themselves by supplying a cell phone number or some other type of personal information. These approaches can provide a poor user experience and can hurt the uptake of a service.